From the Pharmacist Letter, September 2010:
New Canadian guidelines will clarify how to manage opioid therapy in patients with chronic non-cancer pain.
Opioid use is rising and so are abuse, diversion, and overdoses.
But on the other hand, chronic pain is still often undertreated and can lead to disability, depression, and other problems.
Recommend trying other options first, such as NSAIDs for inflammation, low-dose amitriptyline for neuropathic pain, etc.
Before going to chronic opioids, suggest assessing for substance abuse, getting informed consent, and setting up an opioid agreement.
Use pain severity and functional improvement to guide therapy.
Mild to moderate pain. Suggest codeine or tramadol first...then morphine, oxycodone, or hydromorphone if needed.
Recommend starting with a short-acting opioid...titrating the dose as needed...then switching to a long-acting formulation for maintenance to improve adherence and minimize breakthrough pain.
Suggest BuTrans (buprenorphine) for patients who can benefit from a once-a-week patch for moderate pain.
Severe pain. Recommend starting with morphine, oxycodone, or hydromorphone...and stepping up to fentanyl if needed.
Reserve methadone for the most resistant cases. Keep in mind that physicians need a special exemption to prescribe methadone.
Keep an eye on oral morphine equivalents...most patients can be managed on less than 200 mg/day. At higher doses, re-evaluate for tolerance, abuse, or a new cause for the pain. For help, see our chart, Equianalgesic Dosing of Opioids for Pain Management.
Suggest continuing NSAIDs or acetaminophen if they help.
Caution patients to limit acetaminophen doses. Consider recommending a maximum of just 2.6 g/day...instead of 4 g/day...to reduce the risk of developing liver toxicity.
Suggest stopping benzodiazepines before starting opioids...to decrease the risk of sedation and overdose.
Help patients have realistic expectations. Explain that a successful outcome is improving function and reducing pain intensity by about 30%. Also recommend exercise, physical therapy, and adequate rest.
Watch for possible interactions. Oxycodone levels may be increased by 3A4 inhibitors, such as clarithromycin. See our chart, Cytochrome P450 Drug Interactions, for other possible interactions.
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Tools for risk assessment, patient consent, pain contracts, and monitoring are available at:
- http://nationalpaincentre.mcmaster.ca/documents/opioid_guideline_part_b_v5_6.pdf. (See pages 65 to 67)
- NIDA Resource Guide (read before using screening tool below): http://www.drugabuse.gov/nidamed/resguide/resourceguide.pdf